1. Field of Invention
A method, system, apparatus, and computer program product for efficiently relaying information through a wireless radio network.
2. Discussion of the Background
Wireless communications have been adapted for many commercial uses. One use concerns the collection and relay of data from a distributed set of sensors to a central processing facility via one or more transmission and collector towers. In conventional systems, a sensor (e.g., a commercial utility power usage meter or other remote sensor) is connected to a wireless transmitter. The transmitter relays information to a central account facility via a collector tower. The collector may be as part of a radio tower, mounted on a roof top, power poll top or other easement; it may also be mounted in or on a home or commercial building. The preferred embodiment utilizes a tower because it develops the greater range and therefore the lowest cost infrastructure. The transmission time may be random or scheduled. If one or more transmitters are located out of range of the collector tower, repeaters are placed in one or more locations to receive and relay the transmission. Due to cost considerations, these repeaters may not be full duplex devices. That is, the repeaters operate on a schedule where for a portion of time the repeater listens for a broadcast and then for another portion of time the repeater transmits whatever has been relayed. Additional periods exist where the repeater is neither receiving nor transmitting. Full Duplex repeats have the disadvantage of utilizing both receive and transmit bandwidth thus doubling the need of limited RF spectrum to operate the system.
The conventional system utilizing repeaters is characterized by an inefficient flooding of information. That is, information sent by a sensor/transmitter may be received directly by a relay tower and still be repeated by one or more repeaters, therefore wasting the system's RF data capacity.
A certain species of networks called mesh will relay a message through a multiple series of assigned 2-way distributed radio devices. Typically each node may communicate to any other in-range node. This method is intended to extend the reach of a RF signal by creating a routing list stored in communications nodes which may convey a data packet, like a bucket brigade. Such systems typically seek learn the best rout over time and can adapt to changes in the RF environment. If a node fails, such systems seek to self heal by re-routing to the next best set of path nodes. The draw back to this art is the complexity of the distributed data bases required to rout, re-rout, and adapt to a constantly changing RF environment. The temporal coherence at 900 MHz for example is 10 ms; therefore optimal paths may change 100 times a second. Further, RF jamming in the 902 to 928 MHz bands will cause a large amount of path re-routing. A further draw-back is that re-routing uses valuable RF data capacity required for mesh systems to exchange routing lists and to append routing paths to every data message. In addition since any RF transmission propagates not only to an intended node but to all others in range, all redundancy in a mesh causes a proportionate reduction in available RF data bandwidth. Mesh systems must have path memory, change the state of that memory based on changing RF conditions and have a time delay to make that change. In control theory this is a difficult system to make unconditionally stable. Each additional state that a system has exponentially increases its possible failure modes.
Thus, what is desired, as recognized by the present inventors, is an efficient, stable method to selectively relay information within a wireless transmission network that captures the benefits of mesh networking without the inherent risks and deficiencies that are associated conventional mesh networks.